Nonlinear Acoustic Evaluation by Rayleigh Waves for Assessing Concrete Cover Layer Properties

The nonlinear acoustic applied to non-destructive evaluations is a new tool for assessing the properties of concrete with a high sensitivity. Today, the evaluation of concrete properties as a function of the depth is often difficult. In this paper we propose a new approach using Rayleigh waves for the evaluation of nonlinear properties of the concrete cover. It was developed in the lab and requires an experimental approach based on the contribution of numerical modelling. Two methods based on Dynamic Acousto-Elasticity Testing (DAET) which has pump-probe principle are proposed. The application to the case of the evaluation of the carbonation depth in concrete is presented. The first configuration shows high sensitivity in comparison with velocity measurement. The second approach is proposed for on-site measurements and shows high potential to be implemented to the field.